1. Technical Field
This invention relates to development apparatus in electrostatographic reproduction machines such as copiers and printers for electrostatically developing latent images with developer material. More particularly, this invention relates to such a development apparatus that includes a cross-mixing auger device for improved mixing and charging of the developer material.
2. Background Art
It is well known to use toner particles stored within a development apparatus in an electrostatographic reproduction machine, such as a copier or printer, to develop electrostatically formed latent images on an image-bearing member. The toner particles may be stored as such alone or as a component of a two-component developer material, the second component being magnetic carrier particles.
Typically, the development apparatus so used is elongate front-to-back, and is utilized to store, move and mix the developer material. Where two component developer material is employed, moving, mixing and feeding the developer material as such, triboelectrically and appropriately charges the toner and carrier particles therein. The development apparatus also brings the developer material into applying relationship with the images to be developed so that the charged toner particles contained in such developer material are attracted to such images. Such development apparatus are disclosed, for example, in U.S. Pat. Nos. 4,974,023 issued Nov. 27, 1990 to Aimoto et al, and 4,980,724 issued Dec. 25, 1990 to Tanaka. As disclosed, these development apparatus include auger-type mixing devices which are assembled and which have full circumferentially extending blades. The blades are interconnected with longitudinally extending interblade vanes for cross-mixing. Unfortunately, such interblade connecting vanes have a uniform radial extension and are likely to create corner pockets with the blades which can trap developer material thus resulting in mixing inefficiency.
The quality of images developed with charged toner particles as above, depends significantly on the effectiveness and reliability of the development apparatus in triboelectrically charging the toner and carrier particles, and in consistently maintaining desirably high end to end concentration levels of toner particles even when new toner particles are replenished or added at one of such ends. As such, improvements in devices for moving and mixing developer material are very important with respect to improving the quality and reliability of electrostatographic image development. Mixing inefficiency as described above is therefore likely to detrimentally affect image development quality.